Sequential deposition of tantalum nitride using a tantalum-containing precursor and a nitrogen-containing precursor

ABSTRACT

Embodiments of the invention provide a method for forming tantalum nitride materials on a substrate by employing an atomic layer deposition (ALD) process. The method includes heating a tantalum precursor within an ampoule to a predetermined temperature to form a tantalum precursor gas and sequentially exposing a substrate to the tantalum precursor gas and a nitrogen precursor to form a tantalum nitride material. Thereafter, a nucleation layer and a bulk layer may be deposited on the substrate. In one example, a radical nitrogen compound may be formed from the nitrogen precursor during a plasma-enhanced ALD process. A nitrogen precursor may include nitrogen or ammonia. In another example, a metal-organic tantalum precursor may be used during the deposition process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 10/379,438, filed onMar. 4, 2003, now U.S. Pat. No. 6,972,267, which claims benefit of U.S.Ser. No. 60/362,189, filed Mar. 4, 2002, which are both hereinincorporated by reference in their entirety

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to semiconductor processing. More particularly,this invention relates to improvements in the process of depositingrefractory metal layers on semiconductor substrates using sequentialdeposition techniques.

2. Description of the Related Art

The semiconductor industry continues to strive for larger productionyields while increasing the uniformity of layers deposited on substrateshaving increasingly larger surface areas. These same factors incombination with new materials also provide higher integration ofcircuits per unit area on the substrate. As circuit integrationincreases, the need for greater uniformity and process control regardinglayer characteristics rises. Formation of refractory metal layers inmulti-level integrated circuits poses many challenges to processcontrol, particularly with respect to contact formation.

Contacts are formed by depositing conductive interconnect material in anopening on the surface of insulating material disposed between twospaced-apart conductive layers. The aspect ratio of such an openinginhibits deposition of conductive interconnect material thatdemonstrates satisfactory step coverage and gap-fill, employingtraditional interconnect material such as aluminum. In addition, theresistance of aluminum has frustrated attempts to increase theoperational frequency of integrated circuits.

Attempts have been made to provide interconnect material with lowerelectrical resistivity than aluminum. This has led to the substitutionof copper for aluminum. Copper suffers from diffusion resulting in theformation of undesirable intermetallic alloys that require the use ofbarrier materials.

Barrier layers formed from sputtered tantalum (Ta) and reactivesputtered tantalum nitride (TaN) have demonstrated properties suitablefor use with copper. Exemplary properties include high conductivity,high thermal stability and resistance to diffusion of foreign atoms.However, sputter deposition of tantalum and/or tantalum nitride films islimited to use for features of relatively large sizes, e.g., >0.3 μm andcontacts in vias having small aspect ratios.

A CVD process offers an inherent advantage over a PVD process of betterconformability, even in small structures 0.25 μm with high aspectratios. As a result, CVD deposition of tantalum and tantalum nitridewith various metal-organic sources has been employed. Examples ofmetal-organic sources include tertbutylimidotris(diethylamido) tantalum(TBTDET), pentakis(dimethylamido) tantalum (PDMAT) andpentakis(diethylamido) tantalum (PDEAT).

Attempts have been made to use existing CVD-based tantalum depositiontechniques in an atomic layer deposition (ALD) mode. Such attempts,however, suffer drawbacks. For example, formation of tantalum films fromtantalum pentachloride (TaCl₅) may require as many as three treatmentcycles using various radial based chemistries to perform reductionprocess of the tantalum to form tantalum nitride. Processes using TaCl₅may suffer from chlorine contamination within the tantalum nitridelayer.

There is a need, therefore, for tantalum chemistries that may beemployed with fewer reduction steps and shorter cycle times.

SUMMARY OF THE INVENTION

A method for forming a tantalum-containing layer on a substrate disposedin a processing chamber, comprising heating a TBTDET precursor to apredetermined temperature of at least 65° C. to form atantalum-containing gas, forming a tantalum-containing layer upon thesubstrate by adsorption of the tantalum-containing gas onto thesubstrate, reacting a nitrogen-containing process gas with thetantalum-containing layer to produce a layer of tantalum nitride andrepeating forming the tantalum-containing layer and reacting thenitrogen-containing process gas with the tantalum-containing layer toform a layer of tantalum nitride of desired thickness, defining a finaltantalum nitride layer. In accordance with another embodiment of thepresent invention an apparatus is disclosed that carries-out the stepsof the method.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a detailed cross-sectional view of a substrate beforedeposition of a tantalum nitride layer in accordance with one embodimentof the present invention;

FIG. 2 is a detailed cross-sectional view of a substrate shown above inFIG. 1 after deposition of a tantalum nitride (TaN) layer and a coppercontact in accordance with one embodiment of the present invention;

FIG. 3 is a schematic view showing deposition of a first molecule onto asubstrate during sequential deposition techniques in accordance with oneembodiment of the present invention;

FIG. 4 is a schematic view showing deposition of second molecule onto asubstrate during sequential deposition techniques in accordance with oneembodiment of the present invention;

FIG. 5 is a graphic representation showing the growth rate per cycle ofa tantalum nitride layer versus a pre-heating temperature of a TBTDETprecursor, in accordance with the present invention;

FIG. 6 is a perspective view of a semiconductor processing system inaccordance with the present invention;

FIG. 7 is a detailed view of the processing chambers shown above in FIG.6;

FIG. 8 is flow diagram showing a method of depositing a tantalum nitridelayer, in accordance with one embodiment of the present invention;

FIG. 9 is flow diagram showing a method of depositing a tantalum nitridelayer, in accordance with one embodiment of the present invention; and

FIG. 10 is flow diagram showing a method of depositing a tantalumnitride layer, in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION

Referring to FIG. 1 an exemplary structure upon which a tantalum nitridelayer, discussed more fully below, is formed in accordance with thepresent invention is shown as a substrate 10. Substrate 10 includes awafer 12 that may have one or more layers, shown as layer 14, disposedthereon. Wafer 12 may be formed from any material suitable forsemiconductor processing, such as silicon, and layer 14 may be formedfrom any suitable material, including dielectric or conductivematerials. For purposes of the present example, layer 14 includes a void16, exposing a region 18 of wafer 12.

Embodiments of the processes described herein deposittantalum-containing materials or tantalum nitride on many substrates andsurfaces. Substrates on which embodiments of the invention may be usefulinclude, but are not limited to semiconductor wafers, such ascrystalline silicon (e.g., Si<100> or Si<111>), silicon oxide, silicongermanium, doped or undoped polysilicon, doped or undoped silicon waferssilicon nitride and patterned or non-patterned wafers. Surfaces includebare silicon wafers, films, layers and materials with dielectric,conductive and barrier properties and include aluminum oxide andpolysilicon. Pretreatment of surfaces includes polishing, etching,reduction, oxidation, hydroxylation, annealing or baking the substrate.A substrate can be pretreated to be terminated with a variety offunctional groups such as hydroxyls (OH), alkoxy (OR, where R=Me, Et, Pror Bu), haloxyls (OX, where X=F, Cl, Br or I), halides (F, Cl, Br or I),oxygen radicals, aminos (NH or NH₂) or amidos (NR or NR₂, where R=Me,Et, Pr or Bu).

Referring to FIG. 2, formed adjacent to layer 14 and region 18 is abarrier layer 20 containing a refractory metal compound, such astantalum. In the present example, barrier layer 20 is formed fromtantalum nitride, TaN, by sequentially exposing substrate 10 toprocessing gases to form layers of differing compounds on substrate 10.Although not required, in this present case monolayers of differingcompounds may be formed. Tantalum nitride barrier layer 20 conforms tothe profile of void 16 so as to cover region 18 and layer 14. A contact22 is fabricated in accordance with the present invention by formationof a copper layer 24 adjacent to barrier layer 20, filling void 16.Copper layer 24 may be formed using standard techniques (e.g., ALD, PVD,CVD and/or electroplating) and include seed formation and/or fill.

With this configuration, a contact consisting of tantalum nitridebarrier layer 20 and copper layer 24 is formed. Tantalum nitride barrierlayer 20 serves as a seed layer to promote the formation of copper layer24 using, for example, electroplating techniques. Importantcharacteristics that barrier layer 20 should demonstrate include goodstep coverage and thickness uniformity. To that end, tantalum nitridebarrier layer 20 is deposited employing sequential techniques, such asatomic layer deposition.

Referring to FIGS. 2, 3 and 4, one example of forming barrier layer 20employing sequential deposition techniques includes exposing substrate10 to a tantalum-containing gas formed from vaporization of a liquidprecursor (^(t)BuN)Ta(NEt₂)₃ (TBTDET) to form a tantalum-containing gasthat includes TBTDET. It is believed that the initial surface ofsubstrate 10, e.g., the surface of layer 14 and region 18, presentsactive ligands to the tantalum-containing gas. To that end, substrate 10is heated within a range from about 250° C. to about 450° C. and placedin a controlled environment that is pressurized within a range fromabout 1 Torr to about 100 Torr, inclusive. Substrate 10 is exposed to aprocess gas that includes the tantalum-containing gas and a carrier gas.The carrier gas may be Ar, He, N₂, H₂ or combinations thereof and may beused as a purge gas. This results in a tantalum-containing layer beingdeposited on substrate 10. It is believed that the tantalum-containinglayer has a surface of ligands comprising amido (—NEt₂) and imido(=NtBu), shown generally as “a”. The tantalum-containing layer includesbound tantalum complexes with ligands, such that “a”=0-5, often 3 or 4.

The tantalum-containing layer is exposed to another process gas thatincludes a nitrogen-containing gas and a carrier gas to form thetantalum-containing layer forming a barrier layer 20 of tantalumnitride. In this example, the nitrogen-containing gas is NH₃ gas andeither Ar or N₂ is the carrier gas. It is believed that the amido andimido ligands in the exposed surface of the tantalum-containing layerreact with the NH₃ process gas to form byproducts that include radicals(e.g., NH₂, NEt₂, N^(t)Bu, HN^(t)Bu or ^(t)Bu), butene, amines (e.g.,HNEt₂ or H₂N^(t)Bu), (Et₂N)₂ and H₂ among others. In this manner, asurface comprising a layer of tantalum nitride molecules is formed uponsubstrate 10.

Although not required, the tantalum nitride layer may be a monolayer oftantalum nitride molecules. In some embodiments, the process proceedscycle after cycle, until tantalum nitride barrier layer 20 has a desiredthickness achieved, with each cycle having a duration from about 0.01seconds to about 60 seconds, preferably from about 0.1 seconds to about10 seconds, depending upon the processing system employed. The tantalumnitride barrier layer 20 generally has a thickness in the range fromabout 10 Å to about 1,000 Å.

An important precursor characteristic is to have a favorable vaporpressure. Precursors may be a plasma, gas, liquid or solid at ambienttemperature and pressure. However, within the ALD chamber, precursorsare volatilized. Organometallic compounds or complexes that may beheated prior to delivery include any chemical containing a metal and atleast one organic group, such as alkyls, alkoxyls, alkylamidos andanilides. Precursors comprise of organometallic and halide compounds.

Exemplary tantalum precursors that may be heated to formtantalum-containing gases include tantalum compounds containing ligandssuch as alkylamidos, alkylimidos, cyclopentadienyls, halides, alkyls,alkoxides or combinations thereof. Alkylamido tantalum compounds used astantalum precursors include (RR′N)₅Ta, where R or R′ are independentlyhydrogen, methyl, ethyl, propyl or butyl. Alkylimido tantalum compoundsused as tantalum precursors include (RN)(R′R″N)₃Ta, where R, R′ or R″are independently hydrogen, methyl, ethyl, propyl or butyl. Specifictantalum precursors include: (Et₂N)₅Ta, (Me₂N)₅Ta, (EtMeN)₅Ta,(Me₅C₅)TaCl₄, (acac)(EtO)₄Ta, Br₅Ta, Cl₅Ta, I₅Ta, F₅Ta, (NO₃)₅Ta,(^(t)BuO)₅Ta, (^(i)PrO)₅Ta, (EtO)₅Ta and (MeO)₅Ta.

Exemplary nitrogen precursors utilized in nitrogen-containing gasesinclude: NH₃, N₂, hydrazines (e.g., N₂H₄ or MeN₂H₃), amines (e.g., Me₃N,Me₂NH or MeNH₂), anilines (e.g., C₆H₅NH₂), organic azides (e.g., MeN₃ orMe₃SiN₃), inorganic azides (e.g., NaN₃ or Cp₂CoN₃) and radical nitrogencompounds (e.g., N₃, N₂, N, NH or NH₂). Radical nitrogen compounds canbe produced by heat, hot-wires and/or plasma.

Referring to FIGS. 4 and 5, it was discovered that the time required toform tantalum nitride barrier layer 20 may be reduced by heating theTBTDET precursor before formation of the tantalum-containing layer onsubstrate 10. As shown by curve 30 it was found that by heating theTBTDET precursor in the range from about 65° C. to about 150° C., shownas segment 32, the growth rate of the layers of tantalum nitride per ALDcycle may be maximized. Specifically, point 34 shows the growth rate atabout 65° C. being a little less than about 0.9 Å per cycle. Point 36shows the growth rate at about 90° C. being a little less than about 1.2Å per cycle, and point 38 shows the growth rate at about 150° C. beingapproximately 2.0 Å per cycle. A segment 40 of curve 30 shows that fortemperatures below about 65° C., the growth rate of tantalum nitride issubstantially reduced. A segment 42 of curve 30 shows that fortemperatures above about 150° C., the growth rate of tantalum nitride issubstantially reduced. Thus, the slope of a segment 32 of curve 30 showsthat the growth rate of tantalum nitride barrier layer 20 is greater fortemperatures within a range from about 65° C. to about 150° C. comparedto other temperatures for the TBTDET precursor.

Referring to FIG. 6, an exemplary wafer processing system employed todeposit a tantalum nitride layer in accordance with the presentinvention includes one or more processing chambers 44, 45 and 46.Processing chambers 44, 45 and 46 are disposed in a common work area 48surrounded by a wall 50. Processing chambers 44, 45 and 46 are in datacommunication with a controller 54 that is connected to one or moremonitors, shown as 56 and 58. Monitors 56 and 58 typically displaycommon information concerning the process associated with the processingchambers 44, 45 and 46. Monitor 58 is mounted to the wall 50, withmonitor 56 being disposed in the work area 48. Operational control ofprocessing chambers 44, 45 and 46 may be achieved with use of a lightpen, associated with one of monitors 56 and 58, to communicate withcontroller 54. For example, a light pen 60 a is associated with monitor56 and facilitates communication with the controller 54 through monitor56. A light pen 60 b facilitates communication with controller 54through monitor 58.

Referring to both FIGS. 6 and 7, each of processing chambers 44, 45 and46 includes a housing 62 having a base wall 64, a cover 66, disposedopposite to base wall 64, and a sidewall 67, extending there between.Housing 62 defines a chamber 68. A pedestal 69 is disposed withinprocessing chamber 68 to support substrate 10. Pedestal 69 may bemounted to move between cover 66 and base wall 64, using a displacementmechanism (not shown), but is typically fixed proximate to base wall 64.Supplies of processing fluids 70 a, 70 b, 70 c and 71 are in fluidcommunication with processing chamber 68 via a manifold 72. In thepresent example supply 70 a may contain NH₃, supply 70 b may contain N₂and supply 70 c may contain Ar. Process fluid supply 71 includes anampoule 71 a in fluid communication with a vaporizer 71 b. Ampoule 71 aincludes a supply of TBTDET precursor 71 c and is in fluid communicationwith supply 70 c. Ampoule 71 a is in fluid communication with vaporizer71 b via precursor channel 71 d to deliver, to processing chamber 68,precursor 71 c, with the aid of carrier gas in supply 70 c. Ampoule 71a, liquid 71 c and channel 71 d may be heated by conventional heatingmethods, e.g., heating tape in the range from about 65° C. to about 150°C. Regulation of the flow of gases from supplies 70 a, 70 b, 70 c and 71is effectuated via flow valves 73 that are regulated by computercontrol, discussed more fully below. Flow valves 73 may be any suitablevalve. Actuation rates of flow valves 73 may be in the range of amicrosecond to several milliseconds to seconds.

Substrate 10 is heated to processing temperature by a heater embeddedwithin pedestal 69. For example, pedestal 69 may be resistively heatedby applying an electric current from an AC power supply 75 to a heaterelement 76. Substrate 10 is, in turn, heated by pedestal 69, and can bemaintained within a desired process temperature range, with the actualtemperature varying dependent upon the gases employed and the topographyof the surface upon which deposition is to occur. A temperature sensor78, such as a thermocouple, is also embedded in pedestal 69 to monitorthe temperature of pedestal 69 in a conventional manner. For example,the measured temperature may be used in a feedback loop to control theelectrical current applied to heater element 76 by power supply 75, suchthat the wafer temperature can be maintained or controlled at a desiredtemperature that is suitable for the particular process application.Substrate 10 may be heated using radiant heat, e.g., heat lamps orplasma (not shown). A vacuum pump 80 is used to evacuate processingchamber 68 and to help maintain the proper gas flows and pressure insideprocessing chamber 68.

Referring to FIGS. 7 and 8, a method in accordance with one embodimentof the present invention includes heating substrate 10 to a processingtemperature within a range from about 250° C. to about 450° C. at step100. At step 102 processing chamber 68 is pressurized within a rangefrom about 1 Torr to about 100 Torr. This is achieved by activatingvacuum pump 80 to evacuate processing chamber 68. At step 104, theTBTDET precursor is heated in ampoule 71 a within a range from about 65°C. to about 150° C. This forms a tantalum-containing gas that includesTBTDET. At step 106 a purge gas, such as argon, Ar, is flowed intoprocessing chamber 68 for a sufficient amount of time to purgeprocessing chamber 68. The actual time during which Ar is flowed intoprocessing chamber 68 is dependent upon the system employed.

In the present example, Ar is flowed into processing chamber 68 in arange of from about 5 to about 10 seconds to purge processing chamber68. At step 108, the tantalum-containing gas is flowed into processingchamber 68 along with Ar gas to create a tantalum-containing layer onsubstrate 10 that includes TBTDET. To that end, Ar gas from supply 70 cis flowed into ampoule 71 a at a rate in the range from about 50 sccm toabout 2,000 sccm, preferably about 500 sccm. After a sufficient time,which is dependent upon the process system employed, the flow oftantalum-containing gas is terminated, at step 110. In the presentexample, the flow of tantalum-containing gas is terminated after about 5seconds to about 25 seconds after the flow commenced. The flow of Ar gasmay terminate with the flow of tantalum-containing gas. Alternatively,the flow of Ar gas may continue for a sufficient amount of time,depending upon the processing system employed, to ensure removal fromprocessing chamber 68 of tantalum-containing gas and reactionbyproducts, at step 110.

In the present example the time that the flow of Ar gas continues is inthe range from about 5 seconds to about 10 seconds. Subsequently at step112, a nitrogen-containing gas, such as NH₃ gas, is pulsed intoprocessing chamber 68, along with the purge gas for a sufficient amountof time to create a reaction between nitrogen, in the NH₃ gas, and thetantalum-containing layer to form a layer of tantalum nitride. Theresulting layer of tantalum nitride may be a monolayer of tantalumnitride molecules. To that end, the duration of the pulse of NH₃ gas isdependent upon the processing system employed, but in the presentexample the flow of NH₃ gas was in the range from about 5 seconds toabout 35 seconds. The pulse of the nitrogen-containing gas intoprocessing chamber 68 is subsequently terminated, at step 114. The flowof the purge gas may be terminated along with the flow of thenitrogen-containing gas. Alternatively, the flow of the purge gas maycontinue at step 114. In this manner, NH₃ gas and byproducts of thereaction of nitrogen with the tantalum-containing layer are removed fromprocessing chamber 68. This completes one cycle of the sequentialdeposition technique in accordance with the present invention. Theaforementioned cycle is repeated multiple times until barrier layer 20reaches a desired thickness shown in FIG. 2.

It has been found that each cycle results in the formation of a tantalumnitride layer having a thickness within a range from about 0.9 Å toabout 1.2 Å. As a result, at step 116, it is determined whether thetantalum nitride layer has reached a desired thickness employing anyknown means in the art. Were it determined that the tantalum nitridelayer had not reached a desired thickness, then the process wouldproceed to step 108. Were it determined that tantalum nitride layer hadreached a desired thickness, then the process would proceed with furtherprocessing at step 118. An example of further processing could includeformation of a copper layer 24, shown in FIG. 2, employing standardformation techniques, such as electroplating. Further processingincludes a seed layer or a nucleation layer deposited via ALD, CVD orPVD techniques.

Referring to both FIGS. 2 and 7, the process for depositing the tantalumand copper layers 20 and 24 may be controlled using a computer programproduct that is executed by controller 54. To that end, controller 54includes a central processing unit (CPU) 90, a volatile memory, such asa random access memory (RAM) 92 and permanent storage media, such as afloppy disk drive for use with a floppy diskette, or hard disk drive 94.The computer program code can be written in any conventional computerreadable programming language; for example, 68000 assembly language, C,C++, Pascal, Fortran, and the like. Suitable program code is enteredinto a single file, or multiple files, using a conventional text editorand stored or embodied in a computer-readable medium, such as the harddisk drive 94. If the entered code text is in a high level language, thecode is compiled and the resultant compiler code is then linked with anobject code of precompiled Windows® library routines. To execute thelinked and compiled object code the system user invokes the object code,causing CPU 90 to load the code in RAM 92. CPU 90 then reads andexecutes the code to perform the tasks identified in the program.

Referring to FIGS. 7 and 9, a method in accordance with an alternateembodiment overcomes difficulty in having vacuum pump 80 establish theprocessing pressure during the differing processing steps of thesequential deposition process. Specifically, it was found that relyingon vacuum pump 80 to establish the processing pressure might increasethe time required to form a tantalum nitride layer. This is due, inpart, to the time required for vacuum pump 80 to stabilize (settle) inorder to evacuate at a constant rate and thus pump down the processingchamber 68 to establish the processing pressure. To avoid the pumpstabilization problem, vacuum pump 80 may be set to evacuate processingchamber 68 at a constant rate throughout the sequential depositionprocess. Thereafter, the processing pressure would be established by theflow rates of the process gases into process chamber 68. To that end, atstep 200, substrate 10 is heated to a processing temperature within arange from about 250° C. to about 450° C. At step 202 the pump isactivated to evacuate processing chamber 68 at a constant rate. At step204, the TBTDET precursor is heated in ampoule 71 a within a range from65° C. to about 150° C. This forms a tantalum-containing gas thatincludes TBTDET. At step 206 a purge gas, such as argon, is flowed intoprocessing chamber 68 for a sufficient time to purge processing chamber68 and establish a processing pressure. The processing pressure iswithin a range from about 1 Torr to about 100 Torr. Although the exacttime required is dependent upon the processing system employed, in thepresent example, the Ar is flowed into processing chamber 68 in therange from about 5 seconds to about 10 seconds.

At step 208 the tantalum-containing gas is flowed into processingchamber 68 along with Ar gas to create a tantalum-containing layer onsubstrate 10. The flow rates of the tantalum-containing gas and the Argas is established so as to prevent varying the processing pressureestablished at step 206. To that end, Ar gas from supply 70 c is flowedinto ampoule 71 a at a rate of approximately 500 sccm. After about 5seconds to about 25 seconds, the flow of tantalum-containing gas isterminated, with the flow of Ar increased to maintain the processingpressure, at step 210. This continues for a sufficient time to removetantalum-containing gas and reaction byproducts from processing chamber68, typically about 5 seconds to about 10 seconds. Subsequently at step212, a nitrogen-containing gas, such as NH₃ gas, is introduced intoprocessing chamber 68, along with the purge gas for a sufficient amountof time to react nitrogen, contained in the nitrogen-containing gas,with the tantalum-containing layer to form a tantalum nitride layer. Thetantalum nitride layer may or may not be a monolayer of tantalum nitridemolecules. The time required to achieve the nitrogen reaction dependsupon the processing system employed. In the present example, the time isin the range from about 5 seconds to about 35 seconds. The flow rate ofthe NH₃ gas and the purge gas are established so that the processingpressure established at step 206 is maintained. The flow of the NH₃process gas into processing chamber 68 is subsequently terminated, whilethe flow of purge gas is increased at step 214 to maintain a constantprocessing pressure. In this manner, the nitrogen-containing gas andbyproducts of the nitrogen reaction with the tantalum-containing layerare removed from processing chamber 68. This completes one cycle of thesequential deposition technique in accordance with the presentinvention.

The aforementioned cycle is repeated multiple times until barrier layer20 reaches a desired thickness shown in FIG. 2. As a result, at step216, shown in FIG. 9, it is determined whether the tantalum nitridebarrier layer has reached a desired thickness employing any known meansin the art. Were it determined that tantalum nitride layer had notreached a desired thickness, and then the process would proceed to step208. Were it determined that tantalum nitride layer had reached adesired thickness, and then the process would proceed with furtherprocessing at step 218. Generally, the tantalum nitride barrier layer isgrown to a thickness in the range from about 10 Å to about 1,000 Å. Anexample of further processing could include formation of a copper layer24, shown in FIG. 2, employing standard formation techniques, such aselectroplating.

Referring to FIGS. 7 and 10 in yet another embodiment of the presentinvention, removal of byproducts and precursors from processing chamber68 may be achieved by evacuating processing chamber 68 of all gasespresent after formation of each tantalum-containing layer that is yet tounder go a reaction with nitrogen. To that end, substrate 10 is heatedto a processing temperature within a range from about 250° C. to about450° C. at step 300, and the TBTDET precursor is heated in ampoule 71 awithin a range from about 65° C. to about 150° C. at step 302 to form atantalum-containing gas that includes TBTDET. At step 304, vacuum pump80 establishes a processing pressure within a range from about 1 Torr toabout 100 Torr. At step 306 a purge gas, such as argon is flowed intoprocessing chamber 68 for a sufficient amount of time to purgeprocessing chamber 68. The time required to purge processing chamber 68is dependent upon the processing system employed.

In the present example, the time required to purge processing chamber 68is within a range from about 5 seconds to about 10 seconds. At step 308the tantalum-containing gas is flowed into processing chamber 68 alongwith Ar gas to create a tantalum-containing layer on substrate 10. Tothat end, Ar gas from supply 70 c is flowed into ampoule 71 a at a rateof approximately 500 sccm. After a sufficient amount of time, the flowof tantalum-containing gas is terminated, while the flow of Arcontinues. The amount of time during which the tantalum-containing gasflows is dependent upon the processing system employed.

In the present example the tantalum-containing gas is flowed intoprocessing chamber 68 for approximately 5 seconds to about 25 secondsduring step 310. During step 310, the flow of Ar gas into processingchamber 68 continues for a sufficient time to remove thetantalum-containing gas and reaction byproducts from processing chamber68. The duration for which Ar gas is flowed into processing chamber 68is dependent upon the processing system employed, but in the presentexample, is in the range from about 5 seconds to about 25 seconds.

Subsequently, at step 312 the flow of Ar gas is terminated and theprocessing chamber is evacuated of all gases present. At step 314processing chamber 68 is brought to the processing pressure and the Argas is introduced therein. At step 316, the nitrogen-containing gas isintroduced into processing chamber 68, along with the purge gas for asufficient amount of time to react nitrogen in the nitrogen-containinggas with the tantalum-containing layer to form a layer of tantalumnitride. The time required to achieve the nitrogen reaction is dependentupon the processing system employed.

In the present example, the nitrogen-containing gas is flowed intoprocessing chamber 68 in the range from 5 seconds to about 35 secondsduring step 316. The flow of the tantalum-containing process gas intoprocessing chamber 68 is subsequently terminated, while the flow ofpurge gas continues at step 318. In this manner, the tantalum-containingprocess gas and byproducts of the nitrogen reaction are removed fromprocessing chamber 68. At step 320, the flow of Ar gas is terminated andthe processing chamber is evacuated of all gases present therein at step312. This completes one cycle of the sequential deposition technique inaccordance with the present invention.

The aforementioned cycle is repeated multiple times until layer 14reaches a desired thickness shown in FIG. 2. As a result, at step 322 itis determined whether the aforementioned tantalum nitride layer hasreached a desired thickness employing any known means in the art. Wereit determined that tantalum nitride layer had not reached a desiredthickness, and then the process would proceed to step 304. Were itdetermined that tantalum nitride layer had reached a desired thickness,and then the process would proceed with further processing at step 324.An example of further processing could include formation of a copperlayer 24, shown in FIG. 2, employing standard formation techniques, suchas electroplating.

In some embodiments of the processes, tantalum nitride is formed withstoichiometry that includes TaN_(x), were x is in the range from about0.4 to about 2. Tantalum nitride is often derived with the empiricalformulas TaN, Ta₃N₅ Ta₂N or Ta₆N_(2.57). Tantalum nitride is depositedas amorphous or crystalline material. In some metal nitrides, slightvariations of the stoichiometry can have a large impact on theelectrical properties, e.g., Hf₃N₄ is an insulator while HfN is aconductor. Therefore, ALD provides stoichiometric control during thedeposition of product compounds. The stoichiometry may be altered byvarious procedures following the deposition process, such as when Ta₃N₅is thermally annealed to form TaN. Altering the precursor ratios duringdeposition also controls stoichiometry.

Many industrial applications exist for the product compounds andmaterials formed by the various processes of the embodiments described.Within the microelectronics industry, the product compounds may be usedas seed layers, diffusion barrier layers, adhesion layers, insulatorlayers, conducting layers or functionalized surface groups for patternedsurfaces (e.g., selective deposition).

Although the invention has been described in terms of specificembodiments, one skilled in the art will recognize that various changesto the reaction conditions, e.g., temperature, pressure, film thicknessand the like can be substituted and are meant to be included herein andsequence of gases being deposited. For example, sequential depositionprocess may have different initial sequence. The initial sequence mayinclude exposing the substrate to the reducing gas before themetal-containing gas is introduced into the processing chamber. Inaddition, the tantalum nitride layer may be employed for other featuresof circuits in addition to functioning as a diffusion barrier forcontacts. Therefore, the scope of the invention should not be based uponthe foregoing description. Rather, the scope of the invention should bedetermined based upon the claims recited herein, including the fullscope of equivalents thereof.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method for forming a tantalum-containing material on a substrate,comprising: heating a substrate to a deposition temperature within aprocess chamber; heating an ampoule containing a tantalum precursor to apredetermined temperature within a range from about 50° C. to about 170°C. to form a tantalum precursor gas; flowing the tantalum precursor gasthrough a conduit and into the process chamber while maintaining theconduit at a temperature within a range from about 50° C. to about 170°C.; and exposing the substrate to at least sequential pulses of thetantalum precursor gas and a nitrogen precursor during an atomic layerdeposition process to deposit a tantalum nitride material thereon. 2.The method of claim 1, wherein the predetermined temperature of theampoule is within a range from about 65° C. to about 150° C.
 3. Themethod of claim 2, wherein the temperature of the conduit is within arange from about 65° C. to about 150° C.
 4. The method of claim 1,further comprising depositing a nucleation layer on the tantalum nitridematerial.
 5. The method of claim 4, further comprising depositing a bulklayer on the nucleation layer.
 6. The method of claim 5, wherein thebulk layer comprises copper.
 7. The method of claim 1, furthercomprising depositing a bulk layer on the tantalum nitride material. 8.The method of claim 7, wherein the bulk layer comprises copper.
 9. Themethod of claim 1, wherein the nitrogen precursor comprises a radicalnitrogen compound.
 10. The method of claim 9, wherein the radicalnitrogen compound is produced by a plasma during the atomic layerdeposition process.
 11. The method of claim 1, wherein the nitrogenprecursor is selected from the group consisting of nitrogen, ammonia,hydrazine, and azide.
 12. The method of claim 10, wherein the radicalnitrogen compound is selected from the group consisting of N₃, N₂, N,NH, and NH₂.
 13. The method of claim 1, wherein the atomic layerdeposition process further comprises a carrier gas of hydrogen.
 14. Themethod of claim 10, wherein the tantalum precursor is a metal-organicprecursor.
 15. A method for forming a tantalum-containing material on asubstrate, comprising: heating a substrate to a deposition temperaturewithin a process chamber; heating an ampoule containing a tantalumprecursor to a predetermined temperature within a range from about 50°C. to about 170° C. to form a tantalum precursor gas; flowing thetantalum precursor gas through a conduit and into the process chamberwhile maintaining the conduit at a temperature within a range from about50° C. to about 170° C.; exposing the substrate to at least sequentialpulses of the tantalum precursor gas and a nitrogen precursor during anatomic layer deposition process to deposit a tantalum nitride materialthereon; depositing a nucleation layer on the tantalum nitride material;and depositing a bulk layer on the nucleation layer.
 16. The method ofclaim 15, wherein the predetermined temperature of the ampoule is withina range from about 65° C. to about 150° C.
 17. The method of claim 16,wherein the temperature of the conduit is within a range from about 65°C. to about 150° C.
 18. The method of claim 15, wherein the nucleationlayer comprises copper.
 19. The method of claim 15, wherein the bulklayer comprises copper.
 20. The method of claim 15, wherein the nitrogenprecursor comprises radical nitrogen compound.
 21. The method of claim20, wherein the radical nitrogen compound is produced by a plasma duringthe atomic layer deposition process.
 22. The method of claim 15, whereinthe nitrogen precursor is selected from the group consisting ofnitrogen, ammonia, hydrazine, and azide.
 23. The method of claim 21,wherein the radical nitrogen compound is selected from the groupconsisting of N₃, N₂, N, NH, and NH₂.
 24. The method of claim 15,wherein the atomic layer deposition process further comprises a carriergas of hydrogen.
 25. The method of claim 21, wherein the tantalumprecursor is a metal-organic precursor.
 26. A method for forming atantalum-containing material on a substrate, comprising: heating asubstrate to a deposition temperature within a process chamber; heatingan ampoule containing a tantalum precursor to a predeterminedtemperature within a range from about 50° C. to about 170° C. to form atantalum precursor gas; flowing the tantalum precursor gas through aconduit and into the process chamber while maintaining the conduit at atemperature within a range from about 50° C. to about 170° C.; andexposing the substrate to at least sequential pulses of the tantalumprecursor gas and a nitrogen precursor during a plasma-enhanced atomiclayer deposition process to deposit a tantalum nitride material thereon.27. The method of claim 26, wherein the predetermined temperature of theampoule is within a range from about 65° C. to about 150° C.
 28. Themethod of claim 27, wherein the temperature of the conduit is within arange from about 65° C. to about 150° C.
 29. The method of claim 26,further comprising depositing a nucleation layer on the tantalum nitridematerial.
 30. The method of claim 29, further comprising depositing abulk layer on the nucleation layer.
 31. The method of claim 30, whereinthe bulk layer comprises copper.
 32. The method of claim 26, wherein thenitrogen precursor comprises a radical nitrogen compound.
 33. The methodof claim 26, wherein the nitrogen precursor is selected from the groupconsisting of nitrogen, ammonia, hydrazine, and azide.
 34. The method ofclaim 32, wherein the radical nitrogen compound is selected from thegroup consisting of N₃, N₂, N, NH, and NH₂.
 35. The method of claim 26,wherein the atomic layer deposition process further comprises a carriergas of hydrogen.
 36. The method of claim 35, wherein the tantalumprecursor is a metal-organic precursor.
 37. A method for forming atantalum-containing material on a substrate, comprising: heating asubstrate to a deposition temperature within a process chamber; heatingan ampoule containing a metal-organic tantalum precursor to apredetermined temperature within a range from about 50° C. to about 170°C. to form a tantalum precursor gas; flowing the tantalum precursor gasthrough a conduit and into the process chamber while maintaining theconduit at a temperature within a range from about 50° C. to about 170°C.; and exposing the substrate to at least sequential pulses of thetantalum precursor gas and a radical nitrogen compound during aplasma-enhanced atomic layer deposition process to deposit a tantalumnitride material thereon.
 38. A method for forming a tantalum-containingmaterial on a substrate comprising: heating a substrate to a depositiontemperature within a process chamber; heating an ampoule containing ametal-organic tantalum precursor to a predetermined temperature within arange from about 50° C. to about 170° C. to form a tantalum precursorgas; flowing the tantalum precursor gas through a conduit and into theprocess chamber while maintaining the conduit at a temperature within arange from about 50° C. to about 170° C.; exposing the substrate to atleast sequential pulses of the tantalum precursor gas and a radicalnitrogen compound during a plasma-enhanced atomic layer depositionprocess to deposit a tantalum nitride material thereon; depositing anucleation layer on the tantalum nitride material; and depositing a bulklayer on the nucleation layer.